January 1, 2016

Weekend Avalanche Outlook

Happy New Year from the Anchorage Avalanche Center and Alaska Avalanche Information Center!

Avalanche danger in Chugach State Park will remain elevated through the weekend.

Dangerous avalanche conditions exist: careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.

The most prone terrain, for the primary concern of wind slab avalanche, exists mainly in the upper elevations (above ~2500′) on leeward, wind-loaded terrain – especially near peaks and along ridges and cross-loaded gully sidewalls.  Wet avalanches may be a problem in the mid elevations (below ~2500′).

Be mindful of nature’s red flags of avalanche danger like recent avalanches, shooting cracks, a whumphing or collapsing snowpack, wet and saturated snow, etc.  Dangerous areas may be recognized by areas of deeper, wind drifted snow.  Hollow sounding and/or feeling snow, with looser and weaker snow overlying harder, denser snow may also indicate a dangerous, wind-loaded area.  Steep terrain below ~2500′ with wet, heavy, and saturated snow will also be potentially dangerous.

If you are on or exposed to snow-covered terrain steeper than 30 degrees consider the consequences of getting caught in an avalanche!  Examples of unassuming, but potentially dangerous, avalanche terrain include the O’Malley Gully from Glen Alps, Flattop Trail from Glen Alps, and Hunter Pass from South Fork Eagle River.  Make sure you are thinking about terrain traps and how they might compound the consequences of an avalanche.

Forecast strong winds in the mid to upper elevations will inherently make travel uncomfortable and dangerous, regardless of avalanche danger, through Saturday.

Expect cloudy skies, continued chances for snow and rain showers, strong wind (possibly decreasing Sunday), and relatively warm temperatures through the weekend.

While the snowpack is still thin and we haven’t received any significant accumulations of new snow recently, recent extreme strong wind (predominantly from the SE) has redistributed what snow there was and the new snow that has trickled in lately into dangerous wind slabs.  Dangerous D1.5-D2 avalanches have been reported across Chugach State Park the past few days.

On New Year’s Eve, skiers reported D2 wind slabs (WNW aspect, 1-2′ crown, 80-100′ wide, ran ~1000-1500′) on Harp Mountain (Hiland Road – South Fork Eagle River):12.31.15 Harp Wind Slab Collage

Another, smaller slide on the same aspect in the Harp area from New Year’s Eve:12.31.15 Harp Wind Slab from bottom

On Wednesday a skier triggered a wind slab near the top of Peak 3, coming down skier’s right through the rocks, on windloaded WNW facing terrain (click here to view the full observation):  12.30.15p3windslab












Recent wind loading is adding stress to tenuous weak layers and weak interfaces which exist at varying depths in areas with a snowpack.  Faceted interfaces exist between old wind slabs.  Depth hoar and basal facets exist at the ground, and around features like boulders protruding through the snow.